Process of reforming hydrocarbon-containing gases



April 21, 1964 1 C, ECK ETAL 3,130,020

PROCESS OF REFORMING HYDROCARBON-CONTAINING GASES Filed Nov. 20. 1961 4'- s754/Y PURSE conm/mf 27 swr Pff/a L 5,154 wmf pue/M9 A14/rs' Pff/ap Z Fm .nue/Ms 344s:- new/ap IN V ENT ORLS` fra/aver United States Patent O 3,139,029 PRGCESS @E REFGRMIJG HYBRGCAMDN- CCNTAENHJG GASES John C. Eck, Convent, and Edward M. Socle, Arenal,

NJ., assigner-s to Aiiied Chemical Corporation, New York, Nfl., a corporation of New York Filed Nov. Ztl, 196i, Ser. No. 153,562

Claires. (Cl. iS-96) This invention relates to the reformation of hydrocarbon-containing gases such, for exarnple, as natural gas, hydrocarbon gases obtained by pyrolysis or cracking operations including oil gas obtained by pyrolysis of oil and colte oven gas obtained by pyrolysis of coal, methane, ethane, propane, butane and higher hydrocarbons, and mixtures containing two or more such hydrocarbons.

industries dependent on natural gas or other gas supply of certain thermal value usually require a standby source of substitute gas of substantially the same thermal value in the event of interruption or curtailment of their normal gas supply. Shut-downs resulting from the lack of a satisfactory substitute fuel gas result in a loss of production and can be very costly.

Moreover, entirely apart from standby uses, many plants employ a reformed gas of denite B.t.u./c.f. as their normal gas supply.

Processes have been suggested for producing a substitute interchangeable fuel gas supply from readily available hydrocarbon gases such as oil gas which can be stored in conventional, relatively inexpensive gas storage tanks. Such processes heretofore available are objectionable for a number of reasons including, among others, that catalytic processes cannot process efciently available gases containing impurities, particularly sulfur, because of catalyst poisoning which takes place when treat- 'ng impure gases. Noncatalytic processes heretofore proposed involve excessive heat losses, and are otherwise ineihcient or require excessively complicated equipment for their practice.

lt is among the objects of the present invention to provide a cyclic, heat regenerative, non-catalytic process for reforming hydrocarbon-containing gas mixtures, which process requires simple and compact equipment for its practice, conserves heat in that the heat input is beneflcially utilized, is simple and eticient in operation, and can be used to reform available gases including gases containing sulfur and other impurities.

Another object of this invention is to provide such process which can be used to reform hydrocarbon gases to provide a gas supply of desired B.t.u./c.f.

Other objects and advantages of this invention will be apparent from the following detailed description thereof.

ln accordance with this invention, hydrocarbon gases, pure or impure, are reformed to produce a reformed gas of desired heating value which will be lower than. the heating value of the starting gas by alternately carrying out blasting or heating steps and a make step in a gasmalring unit constituted of a single vertical shell having therein a top heat regeneration zone, an intermediate combustion zone, and a bottom reforming zone, the free `.spaces of which zones are of substantially the same vol- Zone, desirably, is from l to 100 square feet.

-umetric capacity. The cross-sectional extent of each The blasting or heating step of each of the successive cycle of steps is always carried out in a downward direction. Air or an oxygen-containing gas such as oxygenenriched air is admitted to the top of the heat regeneration zone, passed downwardly therethrough, enters the top of the combustion chamber wherein it supports combustion of a duid fuel, liquid or gaseous, such as oil or fuel gas, supplied to provide the heat for the process, and

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the resultant products of combustion are passed downwardly through the reforming Zone, exiting from the base thereof. YWhen starting up, the fuel introduced into the combustion chamber is ignited, but once steady state operation is reached this becomes unnecessary.

By owing the oxygen-containing gas in a downward direction through the heat regeneration zone and the products or" combustion from the combustion zone in a downward direction through the reforming zone, eiiicient utilization of the heat is obtained. The downward ow of the heating gases results in even distribution thereof throughout the cross-sectional area of the reforming zone. Empioying a heating step in which the flow is in an upward direction invariably results in uneven and inefficient heating because hot gases tend to rise rapidly. The present invention, involving the downward flow of the heating gases under the pressure of the incoming air or oxygen-containing gas supplied to support combustion in the combustion Zone and under the pressure of the owing stream of the products of combustion from the combustion zone into and through the reforming zone results in uniform and ecient heating of the latter. Also, heat generated in the combustion zone tends to rise into the heat regeneration zone immediately thereabove, augmenting the heat stored in the heat regeneration zone during a subsequent make step as hereinafter explained more fully.

The blasting or heating step is carried out until the temperature at the control point in the reforming zone is from 1200 to 2200 F., preferably from about 1500 to i)o F. Desirably the control point is located at about the transverse median of the reforming zone. Once steady state operation is reached, a blasting step of from l to 3 minutes duration, preferably about 11A minutes, will be found effective.

Following the blasting step, a short steam purge of a few seconds duration may be employed, if desired, in the same direction as the blast, to remove combustion gas from the equipment.

Thereafter a make step is run in the opposite direction from the blasting step. The hydrocarbon gas to be reformed is introduced into the base of the reforming zone, passed upwardly therethrough and through the combustion zone and heat regeneration zone in series and the make or reformed gas withdrawn from the top of the heat regeneration zone. The ow of the hydrocarbon gas is controlled to provide a residence time of from 1 to 20 seconds, preferably 3 to l2 seconds, in the single vertical shell containing the reforming, combustion and heat regeneration zones in series. Ey residence time is meant the time elapsed between the entry of a unit volurne of raw gas at the base of the reforming zone and the exit of the reformed gas produced therefrom at the top of the heat regeneration zone.

During the make step, the temperature at the control point is within the range of from ll0 to 2200 F., preferably 1200 to l800 F. Different temperatures within this range are used depending upon the particular hydrocarbon gas subjected to reformation. Thus, as a general rule, oil gas is reformed at a lower temperature than coke oven gas, both Within this range. At the beginning of the make step the temperature at the control point is sufficiently above about 1200 F. so that at the end of the make step the temperature is not substantially below 1200" "1 When the temperature falls below about l200 l?. at the control point, the malte step is stopped and after the steam purge, a blast step is carried out to restore heat to the reforming zone.

The pressure of the raw gas entering the base of the reforming zone is from l psig. to l0 psig. The pressure of the make gas leaving the heat regeneration zone is from 10 inches to 100 inches water gauge. The make step of each of the successive cycles is always carried out in an upward direction through the reforming, combustion and heat regeneration Zones. Thus the raw gas enters the reforming zone at its base and the gas and reformed gaseous products after flowing through the combustion zone, which is the zone of highest temperature, flow through the heat regeneration zone where the gases give up heat to this zone. The heat thus removed from the exiting make gas is employed to heat the oxygen-containing gas used in the succeeding blasting step.

Residence time, temperature and pressure are interrelated and the limits of the ranges of these conditions given are critical. In general, longer residence times and/ or higher temperatures within the ranges given result in reformed gas having higher hydrogen content and lower B.t.u./c.f. Thus, to produce a low gravity gas of relatively low B.t.u./c.f. higher temperatures and/or longer residence times within the ranges above given are employed. For the production of relatively high B.t.u./c.f. gases, shorter residence times and/ or lower temperature within the ranges above given are employed. By proper choice of residence time and temperature, and operating with an exiting make gas pressure below l() inches water gauge, fuel gas of desired B.t.u./c.f. and speciiic gravity results. As long as these conditions are maintained substantially ixed for any given raw gas, a make gas results of substantially constant B.t.u./c.f. and specic gravity.

Following the make period, a steam purge of a few seconds duration in the same direction as the make gas is carried out to remove combustible gas from the respective zones prior to the blasting step of the next cycle. After this purge the steps above disclosed are repeated.

The accompanying drawing, forming a part of this specification, shows for purposes of exemplification, a vertical'section through a preferred form of single shell unit in which the process of this invention can be carried out. It will be appreciated that this invention is not limited to use of the equipment disclosed in the drawing.

In the drawing, 19 is a single shell unit in the form of an upright cylinder or other shaped metal shell 11 lined with suitable heat insulation 12 having contiguous thereto a refractory lining 13, preferably of re brick. The shell is divided into three zones, namely, a base reforming zone 14, an intermediate combustion zone 15, and a top heat regeneration zone 16. The combustion zone 15 is constituted of an unobstructed space 17 which is in permanently free communication with the base of the heat regeneration zone 16 and the top of the reforming zone i4.

ln the embodiment of the invention shown in the drawing, the heat regeneration zone 16 and the reforming zone 14 have staggered checkerbrick 18 therein. These checkers, for example, may be standard rebrick splits of 1% inches x 41/2 inches x 9 inches, or other suitable dimensions. They are arranged in staggered rows with the bottom row resting on suitable supports so as to obtain optimum distribution of the gas passed through these zones. The checkers, however, while preferred, need not be used; some or all the checkers shown in the drawing can be eliminated. Of course, if all of the checkers are eliminated, the three zones will be completely unobstructed, and the shell i0 will then consist of a refractory lined vertical chamber.

The free spaces in the three zones 14, 15 and 16 are of approximately equal volumetric capacity; by free space @z The height of each zone preferably is from 7 to 70 feet. It will be appreciated that the above dimensions are exemplary and reasonable variations in the dimensions may be made as long as the resultant vertical shell has the three Zones, with the free spaces therein of approximately equal volumetric capacity.

The top of the heat regeneration zone is provided with an oxygen gas inlet 21, a steam purge line 22 and a reformed gas oftake 23, all controlled by suitable valves not shown. The combustion zone 15 has a uid fuel supply line 24 as shown in the drawing. A stack 25 leads from the base of the reforming zone 14. Raw gas to be reformed is introduced into this stack through line 26. Steam for purging the equipment after the make is supplied through line 27. These lines and the stack are equipped with conventional valves to vent the stack to the atmosphere or a waste heat boiler during the blast and close the stack and permit the flow of raw gas during the make and steam during the steam purge following the make. As conventional, all of the valves are operated in desired timed sequence automatically to carry out the successive cycle of steps herein disclosed.

Raw gases of any available hydrocarbon composition having a B.t.u./c.f. higher than that of the desired reformed gas can be used. These gases may be oil gas obtained by steam pyrolysis of oil, coke oven gas, natural gas, hydrocarbon gases obtained by pyrolysis or cracking operations, pure methane, ethane, propane or butane or mixtures thereof, or pure or impure synthetic hydrocarbon gaseous mixtures. Any suitable fuel, liquid or gaseous, may be used during the blasting step.

The reforming process of this invention is useful for the production of fuel gas possessing a large range of B.t.u./ c.f. ratings. Ratings as low as about 200 B.t.u./c.f. and as high as a value just below the rating possessed by the original raw gas may be produced. Thus, town gases can be produced possessing a B.t.u./c.f. rating eminently useful for domestic appliances and for the heating of homes. In addition, raw gases can be reformed to produce gases of high hydrogen content, if desired. Such high hydrogen-containing gases may be readily purified and hence used for the commercial production of hydrogen. Alternatively, gases containing a high hydrogen and carbon monoxide content can be produced. Such gases are useful for such organic syntheses as the reaction of the two principal products, carbon monoxide and hydrogen, in the presence of a suitable catalyst to produce methanol.

The make gases can be blended with the blast gases in any desired proportions to produce a mixed gas having the desired chemical composition attainable by mixing these gases. For example, a make gas comprised of approximately 73% hydrogen can be combined in proper proportions with the blast gas comprising about 80% nitrogen to produce a mixed gas suitable for the preparation of ammonia and other compounds.

The following examples are given to illustrate the invention; it will be appreciated that this invention is not limited `to these examples.

Examples l-7 relate to the apparatus disclosed herein, wherein the following conditions were employed; a blast period of 1% minutes duration, a make period of the same duration, in each case followed by a steam purge of 5 seconds inthe same direction as the blast which was always downwardly after the blast, and a second steam is meant the space between, above and below, the checkers in each zone when a checkerbrick-containing zone is used and the entire space of the zone when a checkerbrick-free zone is used. This is important to obtain the proper blasting step in each of the examples involved the intobalance between the heat generated in the combustion chamber, utilized in the reforming zone, and recovered in the heat regeneration zone to permit operation with most e'icient utilization of the heat input. The interior crosssectional area of each of the heat regeneration zone and the reforming zone (disregarding the checkers) is preferably from l to 100 square feet. For a cylindrical unit, as preferred, the interior diameter is from l to 12 feet.

duction of 5.6 cubic feet of air to the top of the heat regeneration zone for each cubic foot of coke oven gas fuel passed to the combustion zone.

Examples 1-3 involve the reforming of oil gas; Examples 4-6 involve the reforming of coke oven gas with checkers being present in the reforming apparatus; and Example 7 involves the reforming of coke oven gas in the absence of said checkers.

The operating conditions employed are given in Table I and the results obtained therefrom are given in Table Il. ln Table I the top temperature referred to is the temperature at approximately the mid-point of the heat rewardly therethrough, passing the thus heated gas into the combustion zone where it supports combustion of fuel introduced into said combustion zone, passing the resultant products of combustion downwardly through generation zone 16 as determined by a thermocouple 5 the combustion zone and heat reforming zone and withposltioned at this point. The center temperature 1s the drawing same from the base of the heat reforming zone temperature at approximately the ltransverse median of thus heating said heat reforming zone to a temperature the combustion zone as determined by a thermocofuple at the base of said heat reforming zone of from 1200 positioned 1n the refractory lining of the combustion zone to 2200 F., and after the blasting step conducting a make at 1ts transverse median. The range of temperatures given 10 step of from 1 to 3 minutes duration in a reverse direcfor the center temperature represents temperature thus tion to the direction of flow in the blasting step, said detemined throughout -both the blast and make steps once make step involving introducing a hydrocarbon-containsteady state operation is reached. The bottom temperaing gas into the base of the heat reforming zone, passing ture is the temperature at approximately the transverse the hydrocarbon-containing gas and the reformed gases median of the reforming zone 14 as determined by la 15 produced therefrom upwardly through the combustion thermocouple placed in the refractory lining of the reand regeneration zones, and withdrawing the resultant forming zone at approximately the transverse median make gas at a pressure of from 10 inches to 100 inches thereof. The temperatures given show the range of temwater gauge from the top of the heat regeneration zone, peratures at this point throughout both the blast and make the residence time of the hydrocarbon gas and the resteps. formed gas produced therefrom being from 1 to 20 sec- Table I Raw Gas l Oil Gas Coke Oven Gas Example No 1 2 3 4 5 6 7 Gas Feed Ramon. M 146.7 78.2 65.0 20 20 20 20.5 Top Temperature, F 340-1, 520 540-1, 530 1, oso-1,560 430-1, 030 30o-1, 040 530-1, 140 710-900 Center Temperature, 1,600-1,610 1, riso-1,605 1, 710-1, 720 1, 710-1, 690 1, 790-1, 770 1,820-1,800 1, 740-1,720 Bottom Temperature, F.

(eontro1p0int) 1,240-1, 150 1,250-1,220 1,380-1, 290 L400-1,310 1,300-1,210

Table II Raw Gas Gas Oil Gas Gas Coke Oven Gas Feed Feed Example No 1 2 3 4 5 6 7 Gas Analysis' 2.3 1.2 0.6 1.8 1.2 2.0 1.4 1.5 1.5 0.5 1.2 0.5 1.1 0.1 0.5 0.4 0.4 0.6 11.5 0.9 0.0 0.5 1.2 0.0 0.1 0.0 0.3 20.9 3.3 2.1 2.3 3.4 1.6 1.3 0.9 1.3 0.4 0.7 0.2 0.6 0.4 0.5 0.8 0.5 0.7 2.5 3.8 2.9 2.4 1.6 1.4 1.0 1.0 1.2 21.1 55.3 71.8 72.3 54.5 67.0 72.4 73.4 67.1 2.3 4.1 6.9 0.8 5.4 7.8 10.7 11.0 8.2 26.1 21.6 7.2 10.5 23.8 10.0 4.0 3.4 8.3 5.0 0.4 0.2 0.2 2.2 0.2 1.2 1.3 0.0 N2 7.4 7.5 7.5 7.5 6.6 0.0 6.7 6.6 10.8 Gas,B.t.u./c1.. 1,051 518 332 423 559 391 373 360 378 Gas, Sp. Gr 0.55 0.35 0.30 0.35 0.30 0.25 0.24 0.29.

It will be noted that the present invention provides a cyclic, heat regenerative, non-catalytic process for reforming hydrocarbon-containing gas mixtures in simple, compact equipment making the process eminently satisfactory for use as a standby procedure for producing a substitute interchangeable fuel gas supply of desired B.t.u./c.f. as well as an efficient and economical procedure for producing a reformed gas of definite B.t.u./c.f.

Since certain changes may be made in carrying out the reforming process herein disclosed, without departing from the scope of this invention, it is intended that all mat-ter contained in the above description and shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. The process of reforming hydrocarbon-containing gases carried out in a single vertical shell having therein a top heat regeneration zone, an intermediate combustion zone, and a bottom reforming Zone, the intermediate combustion zone being in permanently open and free communication with the heat regeneration zone thereabove and the reforming zone therebelow and the zones being of approximately the same volumetric capacities, which process comprises a blasting step of from 1 to 3 minutes duration always downwardly through said zones involving introducing an oxygen-containing gas into the top of the heat regeneration zone and passing it downonds, and repeating the aforesaid cycle of blasting and make steps.

2. The process as defined in claim 1, in which following the blast and make steps of each cycle, steam is passed in the same direction as the respective blast and make steps.

3. The process of reforming hydrocarbon-containing gases carried out in a single vertical shell having therein a top heat regeneration Zone, an intermediate combustion zone, and a bottom reforming zone of substantially the same volumetric capacities, which process comprises successive cycles of steps, each cycle comprising iirst a blast and thereafter a make step, the blast step always taking place in a downward direction through the heat regeneration, intermediate combustion and bottom reforming zones in series and involving introducing air into the top of the heat regeneration zone, flowing it downwardly therethrough passing the thus heated air into the combustion zone where it supports combustion of iiuid fuel introduced into said combustion zone, passing the resultant products of combustion downwardly through the combustion and heat reforming zones and withdrawing them from the base of the heat reforming zone thus heating said heat reforming zone to a temperature at the base of said heat reforming zone of from 1500 to 17OG F., said blasting step being continued for from 1 to 3 minutes, and after the blasting step carrying out the make step by passing in a reverse direction a hydrocarbon-containing gas introduced into the base of the heat reforming zone, passing the hydrocarbon-containing gas and the reformed gases upwardly through the reforming, combustion and regeneration zones in series, and withdrawing the make gas from the top of the heat regeneration zone, the make step being continued for from 1 to 3 minutes and repeating the aforesaid cycle of blasting and make steps.

4. The process of reforming hydrocarbon-containing gases carried out in a single vertical shell having therein a top heat regeneration zone, an intermediate combustion zone, and a bottom reforming zone of substantially the same volumetric capacities, the heat regeneration zone and the reforming zone containing checkers and the combustion zone being constituted of a substantially unobstructed free space, which process comprises successive cycles of steps, each cycle comprising first a blast and thereafter a make step, the blast step always taking place in a downward direction through the top regeneration, intermediate combustion and reforming zones in series and involving introducing air into the top of the heat regeneration zone, flowing it downwardly therethrough, the thus heated air entering the combustion zone where it supports combustion of fuel gas introduced into said combustion zone, passing the resultant products of combustion downwardly through the combustion and heat reforming zones and withdrawing them from the base of the heat reforming zone, thus heating the checkers in said heat reforming zone to gas reforming temperatures within the range of from 1200 to 2200 F. at the base of said heat reforming zone, and after the blasting step carrying out the make step by passing in a reverse direction a hydrocarbon-containing gas introduced into the base of the heat reforming zone, passing the hydrocarbon-containing gas and the reformed gases thus produced upwardly through the reforming, combustion and heat regeneration zones in series, and withdrawing the reformed gas from the top of the heat regeneration zone and continuing the make step until the temperature at the base of said heat reforming zone is below 1200 F.,

thereafter discontinuing the make step and repeating the aforesaid cycle of blasting and make steps.

' 5. The process of reforming hydrocarbon-containing gases carried out in a single vertical shell having therein a top heat regeneration zone, an intermediate combustion zone, and a bottom reforming zone of substantially the same volumetric capacities, which process comprises successive cycles of steps, each cycle comprising rst a blast and thereafter a make step, the blast step always taking place in a downward direction through the top regeneration, intermediate combustion and bottom reforming zones in series and involving introducing air into the top of the heat regeneration zone, owing it downwardly therethrough, the thus heated air entering the combustion zone where it supports combustion of fuel gas introduced into said combustion zone, passing the resultant products of combustion downwardly through the combustion and heat reforming zones and withdrawing them from the base of the heat reforming zone, thus heating said heat reforming zone to gas reforming temperatures within the range of from 1200 to 2200 F. at the base of said heat reforming zone, and after the blasting step carrying out the make step by passing in a reverse direction a hydrocarbon-containing gas by introducing it into the base of the heat reforming zone, passing the hydrocarbon-containing gas and the reformed gases thus produced upwardly through the reforming, combustion and heat regeneration zones in series, and withdrawing the reformed gas from the top of the heat regeneration zone and continuing the make step until the temperature at the base of said heat reforming zone is below 1200" F., thereafter discontinuing the make step and repeating the aforesaid cycle of blasting and make steps.

References Cited in the le of this patent UNITED STATES PATENTS 

1. THE PROCESS OF REFORMING HYDROCARBON-CONTAINING GASES CARRIED OUT IN A SINGLE VERTICAL SHELL HAVING THEREIN A TOP HEAT REGENERATION ZONE, AN INTERMEDIATE COMBUSTION ZONE, AND A BOTTOM REFORMING ZONE, THE INTERMEDIATE COMBUSTION ZONE BEING IN PERMANENTLY OPEN AND FREE COMMUNICATION WITH THE HEAT REGENERATION ZONE THEREABOVE AND THE REFORMING ZONE THEREBELOW AND THE ZONES BEING OF APPROXIMATELY THE SAME VOLUMETRIC CAPACITIES, WHICH PROCESS COMPRISES A BLASTING STEP OF FROM 1 TO 3 MINUTES DURATION ALWAYS DOWNWARDLY THROUGH SAID ZONES INVOLVING INTRODUCING AN OXYGEN-CONTAINING GAS INTO THE TOP OF THE HEAT REGENERATION ZONE AND PASSING IT DOWNWARDLY THERETHROUGH, PASSING THE THUS HEATED GAS INTO THE COMBUSTION ZONE WHERE IT SUPPORTS COMBUSTION OF FUEL INTRODUCED INTO SAID COMBUSTION ZONE, PASSING THE RESULTANT PRODUCTS OF COMBUSTION DOWNWARDLY THROUGH THE COMBUSTION ZONE AND HEAT REFORMING ZONE AND WITHDRAWING SAME FROM THE BASE OF THE HEAT REFORMING ZONE THUS HEATING SAID HEAT REFORMING ZONE TO A TEMPERATURE AT THE BASE OF SAID HEAT REFORMING ZONE OF FROM 1200* TO 2200*F., AND AFTER THE BLASTING STEP CONDUCTING A MAKE STEP OF FROM 1 TO 3 MINUTES'' DURATION IN A REVERSE DIRECTION TO THE DIRECTION OF FLOW IN THE BLASTING STEP, SAID MAKE STEP INVOLVING INTRODUCING A HYDROCARBON-CONTAINING GAS INTO THE BASE OF THE HEAT REFORMING ZONE, PASSING THE HYDROCARBON-CONTAINING GAS AND THE REFORMED GASES PRODUCED THEREFROM UPWARDLY THROUGH THE COMBUSTION AND REGENERATION ZONES, AND WITHDRAWING THE RESULTANT MAKE GAS AT A PRESSURE OF FROM 10 INCHES TO 100 INCHES WATER GAUGE FROM THE TOP OF THE HEAT REGENERATION ZONE, THE RESIDENCE TIME OF THE HYDROCARBON GAS AND THE REFORMED GAS PRODUCED THEREFROM BEING FROM 1 TO 20 SECONDS, AND REPEATING THE AFORESAID CYCLE OF BLASTING AND MAKE STEPS. 